Progress in Superconductivity

The Korean Superconductivity Society (한국초전도학회)
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Effect of Al Doping on the Anisotropy of $MgB_2$ Single Crystals

Al 첨가가 $MgB_2$ 단결정의 비등방성에 미치는 영향에 대한 연구

  • Kang, Byeong-Won (BK21 Physics Program and Department of Physics, Chungbuk National University) ;
  • Lee, Hyun-Sook (National Creative Research Initiative Center for Superconductivity and Department of Physics Pohang University of Science and Technology) ;
  • Park, Min-Seok (National Creative Research Initiative Center for Superconductivity and Department of Physics Pohang University of Science and Technology) ;
  • Lee, Sung-Ik (National Creative Research Initiative Center for Superconductivity and Department of Physics Pohang University of Science and Technology)
  • Published : 2008.04.30
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Abstract

We have studied superconducting properties of $Mg_{1-x}Al_xB_2$ single crystals from reversible magnetization measurements. It was found that the upper critical fields $H_{c2}$ were decreased for both H // c and H // ab as Al is substituted for Mg. As a result, the large anisotropy of $H_{c2}$ observed in pure $MgB_2$, which is considered as one of the characteristics of two-gap superconductor, was decreased with Al doping. On the other hand, the irreversibility fields $H_{irr}$ were increased for x = 0.1 and were significantly decreased for x = 0.2. In contrary to the anisotropy of $H_{c2}$, the anisotropy of $H_{irr}$ was increased as Al concentration increases.

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